Late years, with a view to providing sophisticated design of a vehicle interior and creating a tranquil atmosphere during illumination, various efforts have been made to adopt an indirect illumination technique to a system for illuminating the interior of a vehicle, such as an automobile, during the night etc., in place of a commonly used conventional technique, so-called “direct illumination”. Differently from the direct illumination technique designed to illuminate a target region by direct light from an illumination member capable of emitting illumination light, the indirect illumination technique is designed to reflect illumination light from an illumination member by a wall surface adjacent thereto and illuminate a target region using the reflected light. Thus, the indirect illumination technique can eliminate the disadvantage in the direct illumination technique, such as excessive brightness in the entire vehicle interior or in the illuminated region and the vicinity thereof, so as to create more tranquil/relaxed atmosphere.
As the system for illuminating the interior of a vehicle, such as an automobile, there has been known one type designed to incorporate an illumination member having a light-guiding performance (hereinafter referred to as “light-guiding illumination member”) in a vehicle interior component, and allow light of a light source provided inside or outside the illumination member to be emitted from the illumination member so as to illuminate the vehicle interior by the emitted light.
For example, the following Patent Publication 1 discloses an illumination member comprising a light guide plate incorporated inside a light-transparent panel, and a light source (e.g. light-emitting diode) disposed on the side of the light guide plate, wherein light from the light source enters from a side surface into the inside of the light guide plate and then exits from a front surface of the light guide plate.
The Patent Publication 1 (Japanese Patent Laid-Open Publication No. 2004-90897) discloses an illumination system for a vehicle, in which the above illumination member is disposed in a center console box, an interior ceiling above a rearview mirror, an instrument panel or a door panel.
Generally, an instrument panel installed in a front interior area of an automobile is provided with various components, such a glove box, and various manual operation elements, such as switches and a wind-direction adjusting lever for an air-conditioning system. Therefore, in dark circumstances, such as the nighttime, it is required to allow an occupant, such as a driver, to recognize the shape and position of the instrument panel so as to ensure usability or user-friendliness in using or manually operating such components and manual operation elements.
In the conventional illumination system where the illumination member is incorporated in an instrument panel to ensure the above user-friendliness, illumination light from the illumination member is liable to directly come within the field of view of a driver sitting in a front seat in a vehicle interior and obstruct the driver's view. The illumination light directly coming within the driver's field of view will cause difficulty in driving during the illumination at night etc., and induce an uncomfortable or disturbed feeling in the driver.
Even if an indirect illumination technique is simply applied to the illumination system associated with an instrument panel, illumination light from an illumination member is likely to directly come within the field of view of a driver sitting in a front seat in a vehicle interior and obstruct the driver's view, depending on the position of the illumination member and the direction of the illumination light.